Despite one of the best summers ever for science-fiction movies, there are signs that Hollywood’s 20-year romance with the genre is coming to an end

“THE Lost World Jurassic Park”, Steven Spielberg's clumsily named dinosaur sequel, has pulled in nearly $225m in North America, while “Men in Black”, 1997's runaway hit, has also crossed the $200m threshold. But there is something worrying about both these films and, for that matter, about their sci-fi predecessors, “The Fifth Element”, “Mars Attacks” and the 1996 blockbuster “Independence Day”. None of them is entirely serious; to a greater or lesser degree, all have an element of self-mockery. And self-mockery tolled the knell for a far more illustrious Hollywood genre than sci-fi—the western.

The self-mockery is least apparent in Mr Spielberg's film, which is in the tradition of “King Kong” or “Jurassic Park” itself. But there are tongue-in-cheek moments even so.

“Men in Black” is never serious. It sets up a kind of spoof Batman and Robin, as if the Caped Crusader and his spooky lap-dog were not parody enough. In their place, it offers Tommy Lee Jones and Hollywood's great black hope, Will Smith, as agents of an unofficial government department whose job is “protecting the earth from the scum of the universe”. They exist to make sure that the 15,000 ETs already covertly walking this planet toe the line. Thanks to director Barry Sonnenfeld, it is funny because the stars are encouraged to play it dead straight.

“Mars Attacks”, directed by Tim Burton, is funnier still. In it the Martians really are little green men who quack like ducks and sport craniums that are a cross between a skull and the Mekon of Mekonta—arch-villain of the old Dan Dare comic strip. The film was a commercial flop, less because it followed too hard on “Independence Day” than because it mounted too comprehensive a hatchet job on the American way.

Everything is savaged—from gung-ho generals to flower people. What eventually makes the Martians' heads split is the agony of terrestrial pop music, and it is Tom Jones, not the Men in Black, who saves the world. For audiences, that was perhaps too unusual.

One quibble: the trailers for “Mars Attacks” and “Men in Black” promised more than was delivered. No Martian in “Mars Attacks” says “Nice planet: we'll take it”, and neither Smith nor Jones, wielding a space-zapper almost bigger than himself, admits that he has no idea how to use it.

Luc Besson's “The Fifth Element”, with Bruce Willis as a flying cabbie in the New York city of tomorrow, does not begin as a parody. But its monsters grow tackier by the minute—first giant metallic ladybirds, then gun-toting rhinos, while Gary Oldman's space buccaneer cradles a familiar that is part Dumbo, part Babar the elephant.

Common to all these films is a lack of faith in the genre itself. In the 1950s, such films as ‘The War of the Worlds”, “Them”, “The Thing” and “The Day the Earth Stood Still” believed in themselves and strove to make audiences believe, too. Though the present sci-fi era began tongue-in-cheek with 1977's “Star Wars”, it has had its share of intelligent and thoughtful work.

“Close Encounters of the Third Kind” (1977) set standards for intergalactic converse that this year's “Contact” cannot match; “Blade Runner” (1982) envisaged a future Los Angeles eco-ruin more convincing than anything Luc Besson has conjured up with the aid of digital technology; “Alien” (1979) and “The Terminator” (1984) yielded nothing in terror to “The Thing”. In those days, sci-fi had the courage of its convictions. Hollywood knew it was telling stories so exciting and challenging that audiences would suspend disbelief. Now it is less sure. So it heads off embarrassment by inviting its audience to laugh along with it.

There has been a moment rather like this before. It is a convenient fiction that the commercial flop “Heaven's Gate” (1980) destroyed the western. In reality, the genre that had dominated Hollywood for more than 50 years was already in decline. In “Blazing Saddles” (1974), Mel Brooks reduced the western to bad taste, with flatulence jokes and a racist plot in which a black man is appointed sheriff in order to drive down property values and allow a speculator to prosper.

Others had trodden that self-deprecatory path before: Lee Marvin as the drunken gunman who cannot hit a barn at ten paces in “Cat Ballou” (1965), and Dennis Hopper in “Kid Blue” (1973), who begins by falling off the roof of a train he plans to hijack and ends by failing to rob the factory in which he is reduced to making Santa Claus ashtrays.

Like the current sci-fi lampoons, many of these comic westerns were funny. But they marked the beginning of the end of Hollywood's belief in the genre. In the western's hey-day, when Ben Johnson called Shane “sody-pop” (because he does not drink whiskey), sparking off the roughest bar-room brawl in the history of the western, nobody tittered. Will Kane (Gary Cooper), squaring up to Frank Miller's gang in “High Noon”, is a lone hero “protecting the town from the scum of the universe”. In effect, he is the same as the Men in Black, though nobody laughed at him. Westerns were serious then. Once conviction wobbled, there was no stopping the downward slide. Late attempts to resuscitate the western, such as Clint Eastwood's Oscar-winning “Unforgiven” (1992), were simply spitting in the wind. Hollywood no longer believed in them.

When such projects were given the green light, there was usually something not quite right about them. Lawrence Kasdan's “Silverado” (1985) slavishly reproduced every cliché of the genre and then miscast John Cleese as the sheriff who strides into the saloon, as if on furlough from “Fawlty Towers”. “Maverick” (1994), with Mel Gibson, James Garner and Jodie Foster, was a leaden remake of the old television show, in which Garner had played the leading role.

Science-fiction may now have reached the impasse that westerns did more than a quarter of a century ago. More sci-fi movies are waiting in the wings, among them “Starship Troopers” and “Alien 4: the Resurrection”, but is it time for a change?

Two of the best films of 1997 have been in a genre long out of favour. The police thrillers “Donnie Brasco” and the forthcoming “L.A. Confidential”—Curtis Hanson's riveting account of life in the LAPD in the corrupt 1950s—suggest a way forward.